Production of colored rubber articles



Patented F eb. 14, 1933 UNITED ST TES PATENT OFFICE RUDOLPH KRECH, OFMANNHEIM, WILHELM SCHEURER, 0F LUDWIGSHAFEN-ON-THE- BHINE, AND ADOLPHKOCH, HOCHST-ON-THE-MAIN, GERMANY, ASSIGNORS TO GENERAL ANILINE WORKS,INC., OF NEW YORK, N. Y., A. CORPORATION OF DELA- WARE {RODUCTION OFCOLORED RUBBER ARTICLES 1T0 Drawing. Application filed June 14, 1932,Serial 1T0. 617,258, and in Germany February 28, 1881.

The present invention relates -to the production of colored rubberarticles.

We have found that rubber products (which term is meant to includenatural rubber as well as the synthetic products wh1ch have aconstitution and properties similar to those of natural rubber, as forexample polymerization productsof butadiene hydrocarbons such asbutadiene or isoprene) can be colored in very strong and often verybright yellow shades having excellent fastness properties byincorporating with the rubber products .ormixtures containing them priorto vulcanization water-insoluble azo dyestuffs of the general formulaXXXX in which one of the Xs in each benzene nucleus is a chlorine atom,the other Xs being hydrogen or alkyl groups such as for example themethyl group, and wherein R is the radicle of an arylamide ofacetoacetic acid. Azo dyestuffs of the said kind may be obtained forexample by the action of tetrazotized dichlor-benzidines on arylderivatives of acetoacetic acid amide; they give greenish to reddishyellow shades as a rule.

By reason of the said dyestuiis being practically insoluble in rubber,they do not bleed when the rubber products are worked up; neither dothey give rise. to that phenomenon which is known as blushing orefliorescence when the rubber articles are stored. Furthermore they areinsoluble in benzine which renders them especially suitable for use inconnection with cold vulcanization processes which are advantageouslycarried out in the presence of benzine. Vulcanization products coloredwith the said dyestuiisdo not give off any of the dyestufi when treatedwith hot soap solutions.

The following examples will further illustrate the nature of thisinvention but the invention is not restricted to these examples. Theparts are by weight.

Example 1 A rubber mixture is prepared from 100 parts of crepe rubber,160 parts of calcium carbonate, 50 parts of kaolin, 2.5 parts ofpetrolatum, 5 parts of zinc white, 0.15 part of diphenyl-guanidine, 1part of mercaptobenzothiazol disulphide, 1.5 parts of stearic acid,.3parts of sulphur and 3 parts of the azo dyestufl' obtainable by coupling1 molecular proportion of tetrazotized 3.3-dichlor-4.4-diaminodiphenylwith 2 molecular proportions of acetoacetic acid mxylidide. The mixtureis vulcanized in a Vulcanizationpress for 12 minutes at a steam pressureof 3 atmospheres above atmospheric pressure. The resulting bright yellowvulcanizate may be used for example as a floor coverlng.

Ewample 2 A rubber mixture is prepared from 100 parts of crepe rubber,10 parts of zinc white, 140 parts of calcium carbonate, 43 parts oftalc, 3 parts of paraffin wax, 3 parts of sulphur, 0.4 part of stearicacid, 0.6 part of mercapto-benzothiazol disulphide and 2 parts of theazo dyestuff obtainable by coupling one molecular proportion oftetrazotized 2.2 dichlor 4.4; diaminodiphenyl with 2 molecularproportions of acetoacetic acid mxylidide. The mixture is sprayed ontocopper wires and then vulcanized by treating with open steam for 20minutes under a pressure of 3' atmospheres above atmospheric pressure.

Example 3 A mixture is prepared from 100 parts of crepe rubber, 2.8parts of sulphur, 0.4 part of paraffin oil, 3 parts of stearic acid, 2parts of brown coal tar oil, 2 parts of colophony, 60

parts of calcium carbonate 13.5 parts of zinc for 45 minutes in hot airat 120 C. and in this way a vulcanizate is obtained which is suitablefor the manufacture of rubber shoes.

Example 4 A rubber mixture is prepared from 100 arts of creperubber-,-'40 parts of white actice (rubber oil substitute), 5 parts oflithopone, 2 parts of magnesium oxide and 2 parts of the azo dyestufiobtainable by coupling 1 molecular proportion of tetrazotized2.2'-dichlor-3.3-di-- methyl-4.4-diaminodiphenyl with 2 molecularroportions of acetoacetic acid o-chloranili e. This articles areprepared from this mixture and are vulcanized by im mersing them for 8seconds in a solution of 3 parts of sulphur chloride in 97 parts ofhenzine. The cold vulcanizate thus obtained has a beautiful yellowcolor.

Eeample 5 A mixture is prepared from parts of crepe rubber, 40 arts ofwhite factice (rubber oil substitute 2 parts of lithopone and 2 parts ofthe azo dyestufi obtainable by coupling 1 molecular proportion oftetrazotized 2.-dichlor-4.4'-diaminodiphenyl with 2 molecularproportions of acetoacetic acid o-toluidide, on the mixing rollers,whereupon the mass is dissolved in benzine. Hot vulcanization productsare immersed in this solution whereupon the solvent is allowed toevaporate from the coating and then the latter is vulcanized in thevapors of sulphur chloride. The coatings thus produced have a beautifulyellow coloration.

Example 6 A mixture is prepared from 100 parts of crepe rubber, 2.5parts of sulphur, 0.35 part of thiuram, 5 parts of zinc white, 0.6 partof ozocerite, 0.5 part of stearic acid and 2 parts of the azo dyestuffobtainable by 'coupling'l molecular proportion of. tetrazotized 3.3dichlor-xl-diaminodiphenyl with 2 molecular proportions of. acetoaceticacid anilide. The mass is vulcanized in an iron mould in a vulcanizationpress for 15 minutes at a superatmospheric pressure of 2 atmospheres.The resulting product which has a beautiful yellow color may be used forexample for making bathing caps.

Ewample 7 Amixture is prepared from 100 parts of cpepe rubber, 50 partsof sulphur, 2 parts of magnesium oxide, 2 parts ofmercapto-benzothiazol, 100 parts of titanium dioxide and 5 parts of theazo dyestuii' obtainable by cou pling 1 molecular proportion oftetrazotized 3.3-dichlor-4. i-diaminodiphenyl with 2,.molecularproportions of acetoacetic acid o-chloranilide. The mass is'vulcanizedin a mould by heating for 2% hours under a steam pressure of- 3atmospheres above atmos- I pheric pressure. A hard vulcanizate having abeautiful yellow shade is obtained.

Similar results are obtained by employing, instead of the dyestuflsreferred to in the foregoing examples, dyestuffs which are derived froma tetrazotized benzidine of the kind specified and acetoacetic acidalphaor betanaphthylamide.

What we claim is V 1. The process of producing colored rubber productswhich comprises mixing a rubber product with a water-insoluble azodyestufi corresponding to the general formula:

XX X-X wherein one of the Xs in each benzene nucleus is a chlorine atom,the other Xs being hydrogen or alkyl, and wherein R is the radicle of anarylamide of acetoacetic acid, and then vulcanizing the mixture.

2. Colored rubber products containing a water-insoluble azo dyestufi ofthe general formula:

wherein one of the Xs in each benzene nucleus is a chlorine atom, theother Xs being hydrogen or alkyl, and wherein R is the radicle of anarylamide of acetoacetic acid. 3. Colored rubber products containing awater-insoluble azo dyestufi of the general formula:

XX XX 6. Colored rubber products containing a water-insoluble azodyestufi derived from 2.2-dich1or-3.3-dimethylbenzidine and anacetoacetic acid amide substituted in the amino group by a radicle ofthe benzene series.

7. Colored rubber products containing a water-insoluble azo dyestuflderived from a 3.3-dich1orbenzidine and an acetoacetic acid arylamide.

8. Colored rubber products containing a water-insoluble azo dyestufiderived from a 3.3'-dichlorbenzidine and an acetoacetic acid amidesubstituted in the amino group by a radicle of the benzene series.

9. Colored rubber products containing a water-insoluble azodyestuflderived from 3.3'-dichlorbenzidine and acetoacetic acid m-xylidide.

In testimony whereof we have hereunto set our hands.

RUDOLPH KRECH. WILHELM SCHEURER. ADOLPH KOCH.

